Questions have emerged about the marketing and labelling of organic food after BBC research found artificial chemicals are being used to control potato blight.

Confirmation that copper oxychloride is being used to control the fungal disease has come from the Soil Association.

The association promotes organic farming as being free of artificial chemicals and has admitted that the copper-based blight sprays represent an "achilles heel".

Consumers assume sprays are not used

Organic farmers are also now asking questions about the sprays which the Soil Association says are used as a last resort, but which potato growers say they rely on to produce their crops.

Tom Gilbert, who runs Ballylaggan organic farm in County Antrim, questions whether organic potato production should even be attempted in the British isles because of a climate which almost invariably results in blight infection.

He said: "If you have to spray things to make them succeed, it's not really what the organic ideal is about. I do it with a heavy heart spraying them because I don't really approve of it."

'Under review'

Mr Gilbert, who sells directly from his farm shop, makes a point of telling customers how the produce is grown but down on the high street shoppers seem confused.

"I just assumed that things like that were not used on organic farms," said one.

The BBC's investigation has also found other evidence of disquiet within the organic sector.

The Soil Association has confirmed that the use of the greenish blue powder-based sprays is now limited to eight kilos per hectare - equivalent to three applications during the growing of a potato crop.

With shoppers paying as much as £3 for a small bag of spuds, they may now be asking what exactly does the organic label stand for

An inquiry to the association's technical department has revealed that while copper-based blight sprays are permitted for the time being, the chemicals are now "under review".

All this may leave consumers wondering if there is any evidence of copper residues in potatoes that reach the shops.

The results of the BBC's research though, are reassuring from a food safety point of view. The investigation did not highlight any health concerns.

What is now under the microscope is the definition of organic.

The Soil Association's claim that organically grown crops do not require artificial chemicals seems somewhat blighted and seems to run counter to what is happening down on the farm.

With shoppers paying as much as £3 for a small bag of potatoes, they may now be asking what exactly does the organic label stand for.